Yet labor unions are at their weakest point in a century, too. Employers, backed by politicians of both major parties, have for decades been working systematically to weaken—and, where possible, eliminate—organized labor. Most recently, state legislatures in traditional union strongholds have passed "right-to-work" laws—measures that weaken unions in the private sector. Public employee unions are facing unprecedented attacks on pensions as well.

For the ISO, the defense of our unions—and helping to organize new ones—is central to our political activity. Because they bring together workers in solidarity at the point of production, unions are key to workers' power—the ability to stop capitalist production at its core. As Ralph Chaplin put it in the famous labor song, Solidarity Forever:

They have taken untold millions that they never toiled to earn

But without our brain and muscle not a single wheel can turn

We can break their haughty power, gain our freedom when we learn

That the union makes us strong

In fact, the history of the socialist and labor movements in the U.S. were closely linked for decades. Socialists played critical roles in the big labor battles of the early 20th century, from the general strikes in three cities in 1934 to the rise of the militant Congress of Industrial Organizations that brought millions of workers into the unions for the first time. But as a result of the anticommunist witch-hunts of the 1950s, socialists were systematically driven out of the unions. This meant that the socialist strategy of social movement, anti-racist, class-struggle unionism was marginalized. Although socialists played an important role in the rank-and-file rebellion of the 1960s and 1970s, those struggles were unable to shift the course of the labor movement.

Unchallenged by the left, the labor leaders of what used to be called "Big Labor" have presided over a long decline of the unions. By refusing to confront racism, they avoided organizing the South for decades, allowing large sections of the U.S. to remain almost entirely nonunion. What's more, union officials' strategy of "partnership" with employers has led to concessions in which decades of gains have been lost. The unions' reliance on the Democratic Party has been nothing short of a disaster, as the Democratic administrations of Bill Clinton and Barack Obama have done nothing to halt the business assault on labor. What's more, the Democrats have pushed anti-union trade deals and budget cuts that have had devastating impacts working people.

Despite labor's crisis, union leaders continue to cling to this failed strategy. Sitting atop the union bureaucracy, top labor officials are insulated from the day-to-day pressures of the workplace. They tend to prefer to make deals with employers—even at the cost of more concessions for workers—in order to avoid a strike or other confrontation that would put the union at risk.

For these reasons, the ISO's effort in the unions focuses on rank-and-file workers. Workers on the job—in factories, warehouses, hospitals, and offices—have an interest in standing together against the boss and fighting back. Rather than rely on full-time union officials to make gains, the socialist strategy is to build the organization of the rank and file that can take up the fight even if union leaders are unwilling or unable to do so. In so doing today, we follow the example of the socialists who were at the forefront of the movement in previous eras in connecting the fight against racism and other social issues to the efforts to build a union.

Teachers from the CTU marching through downtown Chicago

The potential for a revival of organized labor exists. The Chicago Teachers Union strike of 2012 provided a glimpse of what social movement unionism could accomplish, as the union won mass support in the working class for its fight to defend public education. At the same time, the struggles of low-wage workers in the Fight for 15 movement show the potential to organize the unorganized.

Those fights—led by young workers—are leading a new generation to discover the truth of the lines Chaplin wrote a century ago: